maybe there can be the both, factions and guilds. i think destiny breaks with the classical faction vs faction of MMOs (at least is the first one I don't identiify different political groups, from what I watch, such as the horde and alliance in WoW) maybe in the "city" there could be player-managed guilds, like in a normal MMO, offcourse built around destiny's mechanics, but also there could be minor conflicts spread accross the solar system, so each guardian could choose which side of the conflict he/she is picking. The keyword here is "minor" I think destiny's objective is not to develop hate between factions, but rather to make your guardian a legend of the solar system, who has traversed thousands of adventures and perils that people will remember from generation to generation, so this guardian must built up it's own destiny (lame word game :p) choosing a faction of these conflicts must not affect the guardian in a serious way, like in WoW, where you can't even talk with members of the other faction, these faction feuds could be limitated to a small region, for example, to factions of space pirates that disputes a moon of saturn, you must choose a faction, but the conflict is locked in that moon, while you are there, you hate players from the other faction, but maybe these pirates have hired you as a merc, so you are actually fighting for the money, not because you hate the other faction. When you go away from the moon, you don't need to fight the player from the other faction, just because you are not paid anymore. Here is an economical reason for choosing a faction, but there could a bunch of other reasons (ideological, racial,territorial, etc.) and the implications of choosing a faction could be different, in this example you only fight in the moon with the other faction (could be the excuse to make battlegrounds) but other factions would ban you to trading, fighting, etc. with members of the other factions, the possibilities could be endless. lastly, according to your definition of guild, the example of the pirates would be a guild, since they are pursuing a common goal, but from what I learnt in games, is that factions are rivals,(stromcloaks and the empire, alliance and horde, humans and locusts) they fight each other and have different ideologies and political structure, while guilds are not necesarly rivals, they could even be allies, like in eve online, where alliances are formed by several corporations, which are a group of people (what you might call guild in a game) so alliances are groups of groups.